In a production process of electronic devices, such as IC devices, an electronic device testing apparatus is necessary for testing finally produced electronic devices.
A test of IC devices by using an electronic device testing apparatus is conducted, for example, as explained below. After conveying IC devices to be tested to above a test head attached with sockets, the IC devices are pressed to be attached to the sockets, so that connection terminals of the sockets are brought to contact with external terminals of the IC devices. As a result, the IC devices are electrically connected to a tester body via the sockets, the test head and a cable. Then, a test signal supplied from the tester body to the test head through the cable is applied to each of the IC devices, a response signal read from each IC device is sent to the tester body through the test head and the cable, consequently, electric characteristics of the IC devices are measured.
The test explained above is often conducted by giving a thermal stress to the IC devices to be tested. As a method of giving a thermal stress to the IC devices, for example, a method of heating the IC devices to a predetermined temperature by a heat plate in advance before conveying them to the test head is used. Also, a method of furthermore providing a heater to a device for conveying (picking up) and pressing the IC devices and heating the IC devices by the heater is used.
To accurately control a heating temperature of the IC devices to be tested, a temperature of the IC devices has to be measured. Here, some kinds of IC devices are equipped with a thermal diode therein, and a temperature of the IC devices can be measured by measuring a voltage of the thermal diode.